Liquid crystal polymer-based prepreg for printed circuit board having low dielectric constant and low dielectric loss, cooper clad laminate, and printed circuit board

Abstract

Disclosed are a prepreg for a printed circuit board having a low dielectric constant and low dielectric loss for ultrahigh-speed communication, a cooper clad laminate, and a printed circuit board. The prepreg for a printed circuit board having a low dielectric constant and low dielectric loss, according to the present invention, comprises: a polymer resin; and a reinforcing material, including a liquid crystal polymer fabric, impregnated in the polymer resin.

Description

Prepregs, copper-clad laminates, and printed circuit boards with low dielectric constant and low dielectric loss characteristics based on liquid crystal polymers

[0001] The present invention relates to a prepreg for a printed circuit board, a copper-clad laminate, and a printed circuit board having low dielectric constant and low dielectric loss characteristics based on a liquid crystal polymer substrate, and more particularly, to a prepreg for a printed circuit board, a copper-clad laminate, and a printed circuit board having low dielectric constant and low dielectric loss characteristics for ultra-high-speed communication.

[0002] With the recent miniaturization of mobile communication devices, satellite broadcast receivers, computers, and other devices, the electronic components used in them are also becoming increasingly miniaturized, complex, highly functional, and highly precise. This, in turn, necessitates higher density and faster signal transmission for the internal circuit board wiring patterns of electronic circuit components. Furthermore, the frequency range of signals used in communication and electronic devices is shifting from the several GHz range to the tens of GHz range and beyond, making the development of electrical insulating materials with superior high-frequency transmission characteristics and substrates utilizing such materials essential.

[0003] Typically, the manufacturing process for rigid printed circuit boards (PCBs) utilizes prepreg and copper-clad laminate (CCL), which are manufactured by impregnating glass fiber fabric with a resin composition. While glass fiber provides strength to the substrate, its inherent properties make it susceptible to breakage during drilling. Furthermore, drilling through-holes in multilayer boards can cause wear on the mechanical drill, shortening its lifespan.

[0004] Accordingly, there is a continuing demand for materials with lower permittivity and dielectric loss for substrate materials used in high-speed communications and multilayer printed circuit boards for data centers, while also developing materials that offer superior workability and reduced process costs.

[0005] The present invention is intended to solve the above-described problems, and an object of the present invention is to provide a prepreg for a printed circuit board, a copper-clad laminate, and a printed circuit board having low dielectric constant and low dielectric loss characteristics for ultra-high-speed communication.

[0006] In order to achieve the above-described purpose, a prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics according to one aspect of the present invention comprises: a polymer resin; and a reinforcing material including liquid crystal polymer fabric impregnated in the polymer resin.

[0007] The liquid crystal polymer fiber may be either a liquid crystal polymer woven fabric or a liquid crystal polymer non-woven membrane.

[0008] The reinforcing material may be a sequential or batch-laminated liquid crystal polymer woven fabric and liquid crystal polymer nonwoven fabric.

[0009] The reinforcing material may be a sequential or batch-laminated liquid crystal polymer woven fabric, liquid crystal polymer nonwoven fabric, and liquid crystal polymer woven fabric.

[0010] The reinforcing material may be a liquid crystal polymer nonwoven fabric, a liquid crystal polymer woven fabric, and a liquid crystal polymer nonwoven fabric laminated sequentially or in batches.

[0011] The polymer resin may further include a crosslinking agent, an initiator, an auxiliary agent, a flame retardant, and a solvent.

[0012] The polymer resin may further include inorganic filler particles and additives.

[0013] The additive may be at least one of an adhesive, a heat-resistant agent, and a particle dispersant.

[0014] According to another aspect of the present invention, a copper clad laminate for a printed circuit board is provided, comprising: a prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, including a reinforcing material comprising a polymer resin and liquid crystal polymer fibers impregnated in the polymer resin; and a copper clad laminate.

[0015] The prepreg may include a woven prepreg comprising at least one liquid crystal polymer woven fabric as a reinforcing material and a nonwoven prepreg comprising at least one liquid crystal polymer nonwoven fabric.

[0016] According to another aspect of the present invention, a printed circuit board is provided, comprising: a prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, including a reinforcing material comprising a polymer resin and liquid crystal polymer fibers impregnated in the polymer resin; and at least one copper-clad laminate for a printed circuit board, including a copper layer.

[0017] According to another aspect of the present invention, a method for manufacturing a printed circuit board is provided, comprising: a step of impregnating a polymer resin with a reinforcing material including liquid crystal polymer fibers to obtain a prepreg; a step of laminating the prepreg and a copper foil layer to obtain a copper-clad laminate; and a step of laminating the prepreg and the copper-clad laminate.

[0018] The prepreg for a printed circuit board having low permittivity and low dielectric loss characteristics according to the present invention is manufactured using a liquid crystal polymer fiber having low permittivity and low dielectric loss, so that it is possible to manufacture a printed circuit board having low permittivity and low dielectric loss characteristics that can be more advantageously used in the ultra-high-speed communication field.

[0019] In addition, when manufacturing prepreg, since woven or non-woven fabric made of liquid crystal polymer, a high molecular weight polymer, is used, the quality of formation of vias and through holes during the printed circuit board process is improved, and the wear of the machine drill is reduced, thereby extending its lifespan, making workability easier and reducing process costs is possible.

[0020] FIG. 1 is a schematic diagram of a prepreg according to an embodiment of the present invention, FIG. 2 is a surface image of a liquid crystal polymer woven fabric, and FIG. 3 is a surface image of a liquid crystal polymer nonwoven fabric.

[0021] Figure 4 is a cross-sectional view of a prepreg according to another embodiment of the present invention.

[0022] Figure 5 is a cross-sectional view of a prepreg according to another embodiment of the present invention.

[0023] Figure 6 is a cross-sectional view of a prepreg according to another embodiment of the present invention.

[0024] Figure 7 is a cross-sectional view of a prepreg according to another embodiment of the present invention.

[0025] Fig. 8 is a table showing the types and ratios of polymer resins, crosslinking agents, initiators, auxiliary agents, flame retardants, solvents, and liquid crystal polymer fibers used in the examples, and Fig. 9 is a table showing the results of dielectric property evaluations of the examples.

[0026] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. However, the embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided so that those skilled in the art may more completely explain the present invention. Although components may be depicted as having a specific pattern or having a predetermined thickness in the attached drawings, this is for convenience of description or distinction, and therefore, even if they have a specific pattern and a predetermined thickness, the present invention is not limited to the features of the depicted components.

[0027] Fig. 1 is a schematic diagram of a prepreg according to an embodiment of the present invention, Fig. 2 is a surface image of a liquid crystal polymer woven fabric, and Fig. 3 is a surface image of a liquid crystal polymer nonwoven fabric. A prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics according to the present embodiment (hereinafter referred to as “prepreg”) includes a polymer resin; and a reinforcing material including liquid crystal polymer fabric impregnated with the polymer resin.

[0028] The polymer resin (110) included in the prepreg (100) may be a phenol resin, an epoxy resin, a polyimide resin, or the like, but a thermosetting resin is generally used. As a resin exhibiting low dielectric properties, it is preferable to use polyphenylene ether.

[0029] The polymer resin (110) may further include a crosslinking agent, an initiator, an auxiliary agent, a flame retardant, and a solvent. The crosslinking agent is for crosslinking the thermosetting resin, and examples of the crosslinking agent include vinylbenzyl ether compound series divinylbenzene, divinylnaphthalene, divinyldiphenyl, styrene monomer, phenol, and an allyl ether compound prepared by reaction of allyl chloride; diene series such as triallyl isocyanurate, triallylicyanurate, 1,2,4-trivinyl cyclohexane, 1,7-octadiene, and 1,9-decadiene; and di-4-vinylbenzyl ether.

[0030] An initiator can be used to initiate and promote crosslinking, and for example, tert-butyl peroxy benzoate, dicumyl peroxide, or di(2-tert-butylperoxyisopropyl) benzene can be used as an initiator.

[0031] Flame retardants are used to impart flame retardancy to the cured product of a polymer resin composition. Due to environmental concerns, it is preferable to use halogen-free materials. Any flame retardant can be used, as long as it does not affect the crosslinking of the base resin and crosslinking agent, and does not affect dielectric properties or heat resistance, imparting high flame retardancy to the polymer resin composition. Furthermore, any non-halogenated additive flame retardant, or any non-halogenated reactive flame retardant that participates in crosslinking and enhances heat resistance, can be used.

[0032] Organic solvents can be used as solvents, for example, ketones such as acetone, methyl ethyl ketone, and cyclohexanone; acetic acid esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as cellosolve and butyl carbitol; aromatic hydrocarbons such as toluene and xylene; dimethylformamide, dimethylacetamide, N-methylpyrrolidone, and tetrahydrofuran, which can be used singly or in combination of two or more.

[0033] In addition, the resin composition of the present invention may further include additives for improving properties such as adhesive strength or heat resistance, and low-k inorganic filler particles for controlling physical properties. As the inorganic filler particles, ceramic powders with a low coefficient of thermal expansion and low dielectric loss, such as spherical silica, hollow silica, fused silica glass, forsterite, steatite, and cordierite, may be used. The additives may be at least one of an adhesive, a heat-resistant agent, and a particle dispersant.

[0034] The prepreg (100) includes liquid crystal polymer fibers as a reinforcing material within a polymer resin (110). The liquid crystal polymer fibers (120) are formed by weaving liquid crystal polymers into fibers, and the liquid crystal polymer fibers (120) exhibit low dielectric constant and low dielectric loss characteristics of the liquid crystal polymer, thereby affecting the performance of a printed circuit board in which the prepreg (100) is used.

[0035] The liquid crystal polymer fiber (120) may be either a liquid crystal polymer woven fabric or a liquid crystal polymer non-woven membrane. Referring to FIG. 2, the liquid crystal polymer woven fabric is a liquid crystal polymer woven into a regular fiber shape, and referring to FIG. 3, the liquid crystal polymer non-woven fabric is a liquid crystal polymer formed into an irregular fiber shape.

[0036] In the case of a liquid crystal polymer woven fabric, since the pores inside the liquid crystal polymer woven fabric are regular, when impregnated with a polymer resin (110), the polymer resin (110) can be easily injected into the pores, resulting in high strength of the prepreg. On the other hand, in the case of a liquid crystal polymer nonwoven fabric, since the liquid crystal polymer is irregularly positioned to form a fiber layer, the pores may be irregular and injection of the polymer resin (110) may be difficult. Accordingly, a prepreg including a polymer resin impregnated with a liquid crystal polymer nonwoven fabric has excellent mechanical processability.

[0037] FIG. 4 is a cross-sectional view of a prepreg according to another embodiment of the present invention, FIG. 5 is a cross-sectional view of a prepreg according to another embodiment of the present invention, FIG. 6 is a cross-sectional view of a prepreg according to another embodiment of the present invention, and FIG. 7 is a cross-sectional view of a prepreg according to another embodiment of the present invention.

[0038] The prepreg (100) according to the present invention is a polymer resin (110) impregnated with liquid crystal polymer fibers (120) (Fig. 4). The liquid crystal polymer fibers (120) may be liquid crystal polymer woven fabrics (121) or liquid crystal polymer nonwoven fabrics (122).

[0039] The prepreg (100) may be a reinforcing material, in which a liquid crystal polymer woven fabric (121) and a liquid crystal polymer nonwoven fabric (122) are sequentially laminated. The liquid crystal polymer woven fabric (121) has a regular fiber structure, which makes it easy for the polymer resin (110) to be injected into the fibers, and therefore has higher strength than the liquid crystal polymer nonwoven fabric (122) which has an irregular structure and thus makes it difficult for the polymer resin (110) to be injected into the fibers. In contrast, the liquid crystal polymer nonwoven fabric (122) has excellent mechanical processability. Therefore, the prepreg (100) including both the liquid crystal polymer woven fabric (121) and the liquid crystal polymer nonwoven fabric (122) can exhibit low dielectric constant and low dielectric loss characteristics while also including two or more reinforcing materials to possess the advantages of each reinforcing material.

[0040] The prepreg (100) illustrated in FIG. 6 is a reinforcing material obtained by sequentially laminating a liquid crystal polymer woven fabric (121), a liquid crystal polymer nonwoven fabric (122), and a liquid crystal polymer woven fabric (121). The outer layer includes a liquid crystal polymer woven fabric (121) with excellent strength, and the inner layer includes a liquid crystal polymer nonwoven fabric (122). In contrast, the prepreg (100) illustrated in FIG. 5 is a reinforcing material obtained by sequentially laminating a liquid crystal polymer nonwoven fabric (122), a liquid crystal polymer woven fabric (121), and a liquid crystal polymer nonwoven fabric (122). The liquid crystal polymer nonwoven fabric (122) with excellent machinability and workability is positioned as the outermost layer, and the inner layer includes a liquid crystal polymer woven fabric (121) with high strength, so that the process can be easily carried out when manufacturing a copper-clad laminate or a printed circuit board using the prepreg (100).

[0041] According to another aspect of the present invention, a copper clad laminate for a printed circuit board is provided, comprising: a prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, including a reinforcing material comprising a polymer resin and liquid crystal polymer fibers impregnated in the polymer resin; and a copper clad laminate.

[0042] A prepreg used in a copper-clad laminate for a printed circuit board (hereinafter referred to as a “copper-clad laminate”) may include a woven prepreg including at least one liquid crystal polymer woven fabric as a reinforcing material and a nonwoven prepreg including at least one liquid crystal polymer nonwoven fabric.

[0043] According to another aspect of the present invention, a printed circuit board is provided, comprising: a prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, including a reinforcing material comprising a polymer resin and liquid crystal polymer fibers impregnated in the polymer resin; and at least one copper-clad laminate for a printed circuit board, including a copper layer.

[0044] According to another aspect of the present invention, a method for manufacturing a printed circuit board is provided, comprising: a step of impregnating a polymer resin with a reinforcing material including liquid crystal polymer fibers to obtain a prepreg; a step of laminating the prepreg and a copper foil layer to obtain a copper-clad laminate; and a step of laminating the prepreg and the copper-clad laminate.

[0045] A polymer resin composition is impregnated into a liquid crystal polymer woven fabric or a liquid crystal polymer nonwoven fabric to produce a prepreg, and then the prepreg is laminated under pressure together with copper foil to produce a copper-clad laminate. The copper-clad laminate can be used with the prepreg to produce a multilayer circuit board using a printed circuit board process.

[0046]

[0047] Hereinafter, the present invention will be described in more detail through examples.

[0048] <Example>

[0049] A resin composition was prepared by designing a resin, a crosslinking agent, an initiator, an auxiliary agent, a flame retardant, and a solvent as shown in Fig. 8 (weight unit: g), and prepregs of Examples 1 to 5 were prepared by varying the shape of the liquid crystal polymer fiber. The obtained prepregs were laminated by multilayer pressure curing and then evaluated. The materials used are as follows.

[0050] Liquid crystal polymer fibers: woven fabric (Meiwa), nonwoven fabric (Kuraray)

[0051] Polymer resin: mPPE (SA-9000, modified PPE oligomer, Sabic)

[0052] Auxiliary: RICON 257 (a rubber copolymer material with benzene groups and double bonds in the side chain) (Cray Valley)

[0053] Crosslinker: TAC (triallyl cyanurate, Evonik)

[0054] Crosslinking agent: BMI (bismaleimide, Nanoco)

[0055] Flame retardant: PX-200 (Daihachi)

[0056] Initiator: Dicumyl peroxide (DCP, 98%, Sigma-Aldrich)

[0057] Solvent: MEK, toluene (Sigma-Aldrich)

[0058]

[0059] [evaluation]

[0060] The method for evaluating the dielectric properties of laminates is as follows.

[0061] 1) Permittivity: A prepreg is manufactured using a liquid crystal polymer as a base material, and after multilayers are pressure-cured to produce a laminate, the dielectric constant is measured at around 10 GHz and 100 GHz using a split cylinder resonator (SCR) and balanced circular disk resonator (BCDR) type measuring device.

[0062] 2) Dielectric loss: A prepreg is manufactured using a liquid crystal polymer as a base material, and after multi-layer pressure curing to produce a laminate, it is measured at around 10 GHz and 100 GHz using a split cylinder resonator (SCR) and balanced circular disk resonator (BCDR) type measuring device.

[0063] Figure 9 is a table showing the results of dielectric property evaluation of examples. Both the laminates of Example 1 using a liquid crystal polymer nonwoven fabric and Examples 2 to 5 using a liquid crystal polymer woven fabric exhibited low permittivity and low dielectric loss, indicating that the prepreg using the liquid crystal polymer also exhibited low permittivity and low dielectric loss characteristics due to the low permittivity and low dielectric loss of the liquid crystal polymer.

[0064] Above, embodiments of the present invention have been described, but those of ordinary skill in the art will be able to modify and change the present invention in various ways by adding, changing, deleting or adding components, etc., within the scope that does not depart from the spirit of the present invention described in the claims, and this will also be considered to be included within the scope of the rights of the present invention.

Claims

1. Polymer resin; and A prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, comprising a reinforcing material comprising liquid crystal polymer fabric impregnated with a polymer resin.

2. In claim 1, A prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, characterized in that the liquid crystal polymer fiber is at least one of a liquid crystal polymer woven fabric and a liquid crystal polymer non-woven membrane.

3. In claim 2, A prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, characterized in that the reinforcing material is a liquid crystal polymer woven fabric and a liquid crystal polymer nonwoven fabric laminated sequentially or in batches.

4. In claim 1, A prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, characterized in that the reinforcing material is a liquid crystal polymer woven fabric, a liquid crystal polymer nonwoven fabric, and a liquid crystal polymer woven fabric laminated sequentially or in batches.

5. In claim 1, A prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, characterized in that the reinforcing material is a liquid crystal polymer nonwoven fabric, a liquid crystal polymer woven fabric, and a liquid crystal polymer nonwoven fabric laminated sequentially or in batches.

6. In claim 1, A prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, characterized in that the polymer resin further contains a crosslinking agent, an initiator, an auxiliary agent, a flame retardant, and a solvent.

7. In claim 1, A prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, characterized in that the polymer resin further contains inorganic filler particles and additives.

8. In claim 7, Additives are, A prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics, characterized by at least one of an adhesive, a heat-resistant agent and a particle dispersant.

9. A prepreg for a printed circuit board having low dielectric constant and low dielectric loss characteristics according to claim 1; and Copper Clad Laminate for printed circuit boards including a copper layer.

10. In claim 9, Prepreg is, A copper-clad laminate for a printed circuit board, characterized by comprising a woven prepreg comprising at least one liquid-crystal polymer woven fabric as a reinforcing material and a nonwoven prepreg comprising at least one liquid-crystal polymer nonwoven fabric.

11. A printed circuit board comprising at least one copper-clad laminate according to claim 9.

12. A step of obtaining a prepreg by impregnating a reinforcing material including liquid crystal polymer fibers into a polymer resin; A step of laminating a prepreg and a copper-clad laminate to obtain a copper-clad laminate; and A method for manufacturing a printed circuit board, comprising the step of laminating a prepreg and a copper-clad laminate.

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